End opening container with improved stacking strength

ABSTRACT

An end opening, end loading container of three-piece construction has strengthened side and end walls, thereby providing improved stacking strength while using a minimum amount of material.

O United States Patent 1191 1111 3,831,834 Elward 1 Aug. 27, 1974 [54]END OPENING CONTAINER WITH 1,697,709 1/1929 Bliss 229/23 R IMPROVEDSTACKING STRENGTH 2,124,409 7/1938 Andrews 229/23 R 3,063,615 11/1962Bronte et al.. 229/23 R [75] I en J n Elward, Novato. Cahf. 3,197,1087/1965 Northway...... 229/23 0 3,434,648 3/1969 Du Barry, Jr... 229/23 R[73] Flbreboard coFpommn San 3,543,994 12/1970 Clark 229/23 BT Franclsw,Cahf' 3,709,425 1/1973 Stapp 229/23 c [22] Filed: Apr. 9, 1973 [21]Appl. No.: 349,205 Primary ExaminerStanley N. Gilreath Attorney, Agent,or Firm-Robert A. Beck [52] US. Cl 229/23 R [51] Int. Cl B65d 5/32 58Field of Search 229/23 R, 23 BT, 23 c, [57] ABSTRACT 229/14 14 16 51 Anend opening, end loading container of three-piece construction hasstrengthened side and end walls, thereby providing improved stackingstrength while [56] References C'ted using a minimum amount of material.

UNITED STATES PATENTS 1,627,311 5/1927 Bliss 229/23 R X 4 Claims, 4Drawing Figures END OPENING CONTAINER WITH IMPROVED STACKING STRENGTHBACKGROUND OF THE INVENTION In recent years there has been a substantialshift in the type of corrugated containers used in packaging from theconventional top opening containers to end opening, end loadingcontainers. Conventional top opening containers are shipped by themanufacturer in the form of flattened tubes. In use, the tube is squaredup, bottom flaps folded and sealed, contents inserted and top flapsfolded and sealed to complete the package.

If the nature of the contents is such that the container itself musthave high vertical stacking strength, a separate collar may be insertedinto the tubular container prior to insertion of the contents. As analternative, flattened tubular containers are available in which avertical collar has been adhered within the container duringmanufacture.

End opening containers are shipped in the form of flat blanks which areformed into containers in the users plant on automatic equipment. Theformed container is open at one end and contents are normally pushedinto it horizontally, also by automatic equipment. In addition to theadvantages of automatic equipment, an end opening container usuallyrequires substantially less material than a top opening container.

Despite the aforementioned advantages, end opening, end loadingcontainers have not been adaptable to packaging of heavy products, suchas bulk prunes, raisins or the like, which themselves do not contributematerially to the stacking strength of the completed package.Unfortunately, insertion of a loose collar into an end opening containeris very awkward and time consuming. Further, applicant is unaware of anycommercial method whereby a collar may be attached to an end openingblank from which a container may be formed with an integral collar.Thus, when such products have been packaged in end opening containersand the containers have been palletized in relatively high stacks,crushing of the containers has resulted from the weight of the productcombined with the low vertical stacking strength of the containers, theonly recourse being to make the entire blank of costly, high strengthmaterial.

PRIOR ART Top opening containers with improved stacking strength aredisclosed in U.S. Pats. such as No. 3,275,217, No. 3,190,533, No.3,063,615 and No. 2,710,134. Top opening three-piece containers are alsowell known in the art, as exemplified by U.S. Pats. No. 2,022,191, No.1,697,709 and 1,627,311. Further, top opening three-piece containerswith increased stacking strength in two vertical walls are disclosed inU.S. Pats. No. 3,197,108 and No. 3,434,648. None of these patentsdisclose an end opening, end loading container with high stackingstrength.

SUMMARY OF THE INVENTION It is an object of the invention to overcomethe briefly described shortcomings in end opening, end loadingcorrugated containers by providing such a container with improvedvertical stacking strength. In the preferred embodiment this isaccomplished by forming the container from three individual parts, aprimary blank and two similar secondary blanks.

The primary blank comprises top and bottom panels, a back panel andfront closure flaps. It is also provided with side closure tabs attachedto the top, bottom and back panels. Each secondary blank comprises aside panel and front and back portions, and each such secondary blank isformed of high stacking strength material, preferably a double layer ofcorrugated paperboard.

When the secondary blanks are combined with the primary blank byattachment of the aforementioned tabs to the side panels of thesecondary blanks, the front and back portions of said secondary blanksextend along the interior surfaces of the front and back walls of thecontainer thereby providing high stacking strength to all vertical wallsof the container.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of the invention willbecome apparent from the following description and accompanying drawingswherein FIG. 1 is a plan view of the inner surface of a primary blankused in formation of the container;

FIG. 2 is a plan view of a secondary blank used in formation of thecontainer;

FIG. 3 is a perspective view showing the primary blank and the secondaryblanks positioned for folding and sealing; and

FIG. 4 is a perspective view of the container in completed conditionready for insertion of contents.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The container of thisinvention is constructed from a primary blank and two similar secondaryblanks. The primary blank forms the top and bottom walls of thecontainer as well as partially forming the back and front walls. Sincehigh stacking strength is neither necessary or desirable in the top andbottom walls and since the major portion of the stacking strengthrequired in the front and back walls is provided by the secondaryblanks, the primary blank may be made of relatively lightweightmaterial. The preferred material is conventional corrugated paperboardwhich is formed from a layer of corrugated medium with a layer oflinerboard adhered to each surface thereof.

The secondary blanks which provide the container with high stackingstrength should be made of material with higher compressive strength ina vertical direction, preferably double corrugated which is formed fromtwo layers of corrugated medium with a layer of linerboard adheredtherebetween and an additional layer of linerboard adhered to theexterior surface of each layer of corrugated medium. To obtain maximumvertical strength from this material, the corrugations in each layer ofmedium should run in a vertical direction in the completed container.

Referring now to FIG. 1, the primary blank comprises front flap 10, toppanel 11, back panel 12, bottom panel 13 and front flap l4 hingedlyconnected in series along scorelines 15, 16, 17 and 18. Top tabs 20,back tabs 21 and bottom tabs 22 are hinged respectively to each side ofthe top, back and bottom panels along scorelines 23 and 24. A scoreline25 in front flap l0 and a scoreline 26 in front flap 14 provide means toassist in opening the container as will be described later herein.

In addition, a tear strip opener may be provided in the back panel ofthe blank if desired. This tear strip 27 comprises parallel cut lines 28and 29 extending transversely across back panel 12 and back tabs 21, andtear tab 30 protruding slightly beyond the free edge of one of the tabs21. Further diagonal cut lines 31, 32, 33, and 34 are provided in theback panel extending inwardly from the junctures of scorelines 16 and 17with scorelines 23 and 24. These cut lines lie at an angle of about 45to scorelines 16 and 17 and extend until they intersect one of theaforementioned transverse cut lines 28 and 29.

All of these previously mentioned cut lines are made on the interiorsurface of the blank and extend only for a limited depth into thepanels, that is, through the interior linerboard of the corrugatedpaperboard and preferably partly through the corrugated medium.

Referring now to FIG. 2, a secondary blank for use in forming thiscontainer is depicted. As previously noted, the secondary blank is madeof double corrugated with the corrugations arranged so that they run ina vertical direction in the completed container. Two secondary blanksare used in each container but, since they are similar in structure,only one will be described. The secondary blank comprises a side panel40, with a front portion 41 and a back portion 42 hinged to therespective ends thereof along scorelines 43 and 44.

Back portion 42 of the secondary blank is dimensioned such that it issubstantially equal in width to one half the width of back panel 12 ofthe primary blank, so that in the completed container the free ends ofback portions 42, which lie along back panel 12, will substantially abuteach other. Front portions 41 are similarly dimensioned with respect tofront flaps and 14 of the primary blank.

As has been previously mentioned, automatic machinery is available inthe marketplace to form the primary blank and secondary blanks describedabove into a completed container. Since this machinery comprises no partof this invention, it will not be described in detail. Only a methodwhich may be used will be described.

Referring now to FIG. 3, the three blanks required are shown in positionfor formation of the container. A pair of secondary blanks are held inposition so that side panels 40 will form the sides of the container.Back portions 42 of the secondary blanks are folded inwardly until theymake an angle of 90 with the respective side panels 40, and therespective free edges of said back portions are in substantial abutment.A suitable adhesive is then applied to the interior surfaces of fronttabs 20, back tabs 21 and bottom tabs 22 of a primary blank and thisblank in then positioned with the interior surface of its back panel 12in face to face contact with the exterior surfaces of back portions 42.

A ram or pusher, represented schematically at 45, then moves leftwardlyin FIG. 3 into contact with the interior surfaces of back portions 42 ofthe secondary blanks. Upon further movement of this ram, the combinationof blanks is pushed through a forming member shown schematically at 46.In passing through the forming member, top panel 11 is folded downwardlyand bottom panel 13 is folded upwardly along scorelines 16 and 17respectively until these panels contact the top and bottom edges of sidepanel 40.

Simultaneously, tabs 20, 21 and 22 are folded inwardly along scorelines23 and 24 into face to face contact with side panels 40. This contact ismaintained for a sufficiently long period to permit the aforementionedadhesive to set.

The completed container, ready for insertion of contents is shown inFIG. 4. Conventionally, the contents of the container are then pushedhorizontally into the open front of the container, front portions 41 ofthe secondary blanks are folded inwardly to a angle and front flaps l0and 14 are closed. Closure of these flaps may be maintained by adhesive,staples, tape or any other suitable means.

In the completed container, top panel 1 1 and bottom panel 13 of theprimary blank form the top and bottom walls respectively of thecontainer. The container side walls are formed from side panels 40 ofthe secondary blanks by attachment to tabs 20, 21 and 22. The back endwall of the container is formed from back panel 12 of the primary blankand back portions 42 of the secondary blanks while the container frontend wall is formed from front flaps l0 and 14 of the primary blank andfront portions 41 of the secondary blanks.

Thus it can be seen that this container provides users with the benefitsof an end loading end opening container, to wit, a minimum use ofpackaging material and adaptability to automatic equipment, while alsoproviding the heretofore unavailable advantage of high stackingstrength. The top and bottom panels, where high stacking strength isunnecessary, may be formed of relatively lightweight, inexpensivematerial, while the relatively expensive, high stacking strengthmaterial is concentrated in the vertical side, front and back walls.Further, this high stacking strength material extends substantiallyentirely around the vertical walls, leaving no weak points.

Means are provided in the front wall of the closed and sealed containerfor ease of opening. In sealing front flaps 10 and 14 to underlyingfront portions 41, glue may be applied to said flaps only in the areasbetween scorelines 15 and 25 and between 18 and 26. Thus, when theseflaps are sealed in closed position, the areas between scoreline 25 andthe free edge of flap l0 and between scoreline 26 and the free edge offlap 14 are not adhered. Thus, fingers may be inserted under these areasand the entire flap may be expeditiously pulled free to open the frontof the container, leaving only front portions 41 to be folded outwardly.

Additional opening means may be provided in the back wall of thecontainer as hereinbefore mentioned. To operate this opening means, teartab 30 in back tab 21 may be grasped and pulled outwardly, thus easilyripping away the entire length of tear strip 27, dividing back panel 12into upper and lower segments. However, these segments of said backpanel are still held firmly in position by the remaining portions ofback tabs 21 which are sealed to side panels 40. In order to completeoperation of this opening means, one need only grasp the free edges ofthe remaining back panel segments and pull outwardly. A minimal outwardforce will split these segments along diagonal cut lines 31, 32, 33, 34,opening the container and providing access to the contents.

Preferably, these containers are provided with opening features in bothfront and back walls. Not only does this permit easy access to thecontents through either end but also, by opening both front and back theempty container may be easily flattened for expeditious disposal.

What is claimed is:

l. A generally rectangular, end opening, end loading container havinghigh stacking strength, constructed from a primary blank and a pair ofsecondary blanks,

said primary blank made of relatively lightweight material andcomprising a top panel, a back panel, a bottom panel and front closureflaps all hingedly connected along parallel scorelines, and tabs hingedalong scorelines to the sides of each of said panels,

each secondary blank made of relatively heavier material having highstacking strength and comprising a side panel and front and backportions hinged to the respective ends of said side panel alongscorelines, each of said portions having a free end remote from suchscoreline,

said container comprising top and bottom walls formed from the top andbottom panels of said primary blank,

side walls formed from the side panels of said secondary blanks byattachment to the tabs of said primary blank,

a back end wall formed from the back panel of said primary blank and theback portions of said secondary blanks,

a front end wall formed from the front closure flaps of said primaryblank and the front portions of said secondary blanks,

whereby said side walls and said end walls comprise a vertical layer ofhigh stacking strength material, and

opening means in an end wall of said container.

2. The container of claim 1 wherein the free ends of said back portionsand the free ends of said front portions are respectively in substantialabutment and said layer of high stacking strength material extendssubstantially entirely around the vertical periphery of said container.

3. The container in claim 1 wherein opening means are provided in eachof said end walls, one of said opening means comprising a transverse,removable tear strip and diagonal, limited depth cut lines in said backwall extending from the corners of said wall inwardly to said tearstrip.

4. The container of claim 1 wherein the material of said primary blankis conventional corrugated paperboard and the material of said secondaryblanks is double corrugated paperboard.

1. A generally rectangular, end opening, end loading container havinghigh stacking strength, constructed from a primary blank and a pair ofsecondary blanks, said primary blank made of relatively lightweightmaterial and comprising a top panel, a back panel, a bottom panel andfront closure flaps all hingedly connected along parallel scorelines,and tabs hinged along scorelines to the sides of each of said panels,each secondary blank made of relatively heavier material having highstacking strength and comprising a side panel and front and backportions hinged to the respective ends of said side panel alongscorelines, each of said portions having a free end remote from suchscoreline, said container comprising top and bottom walls formed fromthe top and bottom panels of said primary blank, side walls formed fromthe side panels of said secondary blanks by attachment to the tabs ofsaid primary blank, a back end wall formed from the back panel of saidprimary blank and the back portions of said secondary blanks, a frontend wall formed from the front closure flaps of said primary blank andthe front portions of said secondary blanks, whereby said side walls andsaid end walls comprise a vertical layer of high stacking strengthmaterial, and opening means in an end wall of said container.
 2. Thecontainer of claim 1 wherein the free ends of said back portions and thefree ends of said front portions are respectively in substantialabutment and said layer of high stacking strength material extendssubstantially entirely around the vertical periphery of said container.3. The container in claim 1 wherein opening means are provided in eachof said end walls, one of said opening means comprising a transverse,removable tear strip and diagonal, limiteD depth cut lines in said backwall extending from the corners of said wall inwardly to said tearstrip.
 4. The container of claim 1 wherein the material of said primaryblank is conventional corrugated paperboard and the material of saidsecondary blanks is double corrugated paperboard.